Strain relieving and dephasing stop means for free piston engines



F. M. LEWIS 2,409,218

STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES Oct. 15, 1946.

Filed Dec. 26, 1944 4 sheets-sheet 1 Get. 15, 1946., 2,409,218

STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES F. M. LEWIS 4 Shets-Sheet 2 Filed Dec. 26, 1944 gnaw bow @o-uycq W,

I Oct. 15, 1946.

F. M. LEWiS 2,409,218 "TRAIN RFJZIIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES Filed Dc. 26, 1944 4 Sheets-Sheet s gnaw WM THANK MLEWJB I 3 @ae/mfi' @0444,

Oct. 15, 1946.

F. M. LEWIS STRAIN RELIEVING AND DEPHASING STOP MEANS FOR FREE PISTON ENGINES Filed Dec: 26, 1944 4 Sheets-$heet 4 Patented on. 15, 1946 2,409,218

UNITED STATES PATENT OFFICE STRMN RELIEVING AND 'DEPHASING STOP MEANS FOR FREE PISTON ENGINES Frank M. "Lewis, Weston, Mass assignor to General Machinery Gorporation, Hamilton, Ohio, a corporation of Delaware Application December 26, 1944, Serial No. 569,871

22 Claims.

free pistons comprise two opposing piston sets which move outward under the force of an igrack-bars broken away, and including certainopcrating features of the invention; Fig. 3 is a cross-section thereof on the line 33 in Fig. 2; Fig. 4 is a central longitudinal section thereof on the line 4-4 in Fig. 2; Fig. 5 is an end view of the device shown in Fig. 2-, with one of the rack-Hears in section; Fig, 6 is an e'nlargedsectional detail of one of the fluid pressure line control valves associated with the means shown in nited fuel charge injected therebetween and mov- Fig. 2; Fig. 7 is a longitudinal sectionaldeta-il of ing inward under direct bounce action of comthe trip control means for the fuel feed pump; pressed gases to compress and ignite the next Fig. 8 is a sectional view of a conventional form fuel charge. The opposing pistons are connected f e p p; Fig. 9 is a modified form of the inin a manner to cause a proper synchronizing of vention embodying a valve in the fuel injection their movements, and in operation of the engine line from the pump to the engine, which valve it is common occurrence for the parts of the is moved bya predetermined dephasing action of synchronizing means to be harmfully stressed due the pistons to relieve injection pressure in such to the sticking or dragging of one of the piston line; Fig. 10 is a fragmentary detail of such modsets, which creates a dephasing condition of the ification; Fig. 11 is another modification of the piston movem nts, invention embodying an electrical control feature The object of the present invention is the profor the fuel feed shut-off; Figs. 12 and 13 are vision of simple and efficient means in connection fragmentary details thereof, and Fig. 14 is a modwith, and automatically operable by, the piston ification of the electrical control means shown in synchronizing means of an engine of this char- Fig. 11. actel" to interrupt the engine Operation when a 2 Referring to the drawings, 1 designates an inendency arises for the pistons to become deternal combustion engine of the free piston type phased or unsynchronized in their motions due havin opposed piston sets, each com-prising a to either set of pistons stick g or dra n in working piston 2 operating in a combustion its action, or to other causes. chamber 3, an air compressor piston 4 operating A further object of the invention is the proviin a chamber 5, and a direct bounce piston 6 cpsion of means for governing the automatic stopcrating in a chamber 1, all for the purpose and ping action of the engine upon a dephasing 0011- in a manner well understood in the art. dition of the pistons occurring, whereby the stop- The two piston sets are connected by suitable ping means will be brought into effective action means to cause them to operate in proper synonly by a predetermined magnitude of the de- 5 chronized relation. In the present instance, this phasing stressess. means includes a rack bar 8 projecting inwardly Another object of the invention is the provision from one piston 4 and a rack-bar 9 projecting inof simple and efhcient means of a cushion nature wardly ffom the other piston 4 through the inner forming a part of the piston synchronizing means end wall of the respective cylinder 5, with the of free pis on engi t0 absorb a d mat rially 4-0 bars in laterally spaced parallel relation at a side reduce engine shock loads, especially when the of the cylinder I0 forming the combustion chamshocks are due to unequal loading, and therefore her 3. A pinion ll (Fig. 2) is interposed beto offer a certain amount of resiliency to the tween the rack-bars, in mesh with each, and has e ine. trunnions i2 journaled in a carriage [block I3 for Further objects and advan ag of e v floating movements therewith lengthwise of said tion will be apparent from the following detailed rack-bars, for the purpose and as hereinafter description, and from the accompanying drawmore fully described; ings illustrating one embodiment thereof, and in The engine is equipped with a fuel injection which pump [5 which is conventionally shown in the Figure l is adiagrammatic View of a free piston dra ing (Fig, 8) a including a charge chamengine q ipped with means embody t in ber l6 receiving its fuel oil supply from a contion, with the pistons at substantially the limit stant pressure supply pump 52 through a pipe of their outward strokes; Fig. 2 is an outer side line 59, 5| and having its discharge to the assoelevation, partly in longitudinal section, of the ciated fuel injection nozzle IQ of the engine synchronizing means for the pistons, with the 55 through the line 20. A plunger .2! is recipro cably movable in the pump casing to force a fuel charge from chamber IE to the nozzle, and is rotatable about its longitudinal axis whereby a controlled metered charge of fuel is admitted to the charge chamber from the pipe 56 during one stroke of the plunger and is ejected therefrom to the fuel nozzle during another stroke thereof. Rotary adjustment of the plunger to vary the fuel feed is efiected by longitudinal movement of a rack-bar 22 in engagement with a pinion 23 on the plunger, as is common in the art. In the present instance, the fuel charge is increased when the rack-bar 22 is moved to the left and is reduced when the bar is moved to the right. The plunger 2| carries a roller on its outer end which travels on a side edge of the rack-bar 9, in the present instance, and is actuated to cause the plunger to eject a fuel charge at a predetermined point in an engine cycle by engagement of the roller with a cam 25 on said rack-bar. This engagement is customarily timed to take place just before the working pistons have reached the ends of their inward or compression strokes.

A control for the pump rack-bar 22 to impart reciprocatory movements thereto to increase or reduce the fuel feed charge to the injection nozzle |9 includes a rod 36 (Fig. 7) connected to or forming a, continuation of the left end, in the present instance, of the pump rack-bar 22. This rod projects at its opposite end into the open end of a cylinder 3| where it connects to a hollow open ended plunger 32 which is reciprocally mounted in a trip sleeve 33 that is slidingly mounted in the cylinder 3|. A compression spring 34 is disposed in the hollow of the members 32 and 33 between the opposed closed ends thereof and exerts an outward moving force on the rod to move the rack-bar 22 tothe right or in fuel feed reducing direction. The movement of the trip sleeve 33 to the left is opposed by a compression spring 35 in the closed or left end of the cylinder 3 I.

A block 36 is slidingly mounted on the rod 30 in spaced relation to the plunger 32 and a compression spring 31 is mounted on the rod between the block and plunger in end-thrust engagement with each and tends to move them apart. Movement is imparted to the block 36 lengthwise of the rod 36 by a lever 36 which is fulcrumed to the engine frame at 39 (Fig. l) and has one end in sliding pivotal connection with the block and its other end connected by a link 46 to a manually operable control lever 4|. This lever is retained in adjusted position by releasable engagement of a hand latch thereon with a ratchet sector 42. The spring 31 opposes the pressure of the spring 34, being normally of greater tension, and the spring 35 opposes and is of greater tension than both springs 34 and 31.

The trip sleeve 33 is held in retracted position, with the spring 35 compressed, by a trip pin 43 operating through a side aperture in the cylinder 3| and engaging at its inner end in an annular recess 44 in the circumference of the sleeve. The outer end of this pin is attached to a piston 45 in a cylinder 46 mounted on the cylinder 3|. A spring 41 applies an inward force to the piston to yieldingly hold the pin in looking engagement within the recess 44 of the trip sleeve 33, and fluid pressure is admitted through a pipe line 48 to the cylinder at the inner side of the piston to move it outward to cause the pin to release the trip sleeve. The line 48, in the present instance, has connection through two branches 49 and 56 with a supply line 5| leading through a pressure pump 52 from a tank, or other suitable supply source 53.

Each branch line 49, 56, has a normally closed valve 55 therein. Each of such valves includes a casing 56 (Fig. 6) preferably secured for lengthwise adjustmentto a convenient part of the engine frame by screws 51 projected through slots 58 in the casing. A valve stem 59 operates in the casing with one end projected therefrom and is adapted, when in one position, to close a crosspassage 66 in the casing which forms a part of the respective branch line 49, 56 in which the valve 55 is disposed. The valve stem has a recess 6| disposed in position to register with the crosspassage 66 and open the respective branch line when the stem is moved inward a slight extent from its outward position. A spring 62 acts on the valve stem to normally hold it in closed-position.

The carriage |3 for the pinion II is in the nature of a cross-head and is guided for movements longitudinally of the engine by upper and lower guides 65 provided in the attachment 66 secured to the side of the engine cylinder ID by screws 67. The rack-bars 8 and 9 of the piston synchronizing means are also guided for reciprocatory movements in the attachment 65 and are held thereby in meshing engagement with the pinion II at opposite sides of its axis. The car- -riage i3 is yieldingly held in central or neutral position by a spring pressed pad 68 at each end engaging an adjustable screw 69 in an end portion it! of the attachment 66, Each pad 68 and its spring H are carried by a cup 12 at the respective end of the carriage. The screw 69 may be locked in adjusted position by a lock nut 13.

A valve opening rod 15 is mounted in each part '10 in line with the movement of the carriage I3 and normally slightly spaced therefrom, so that upon a predetermined movement of the carriage in either direction from neutral position, it will strike one or the other of the rods 15 and, upon a continuation of such movement, move it outward against the tension of a spring 16. Such spring, in the present instance, acts at one end against a stop collar 11 which is adjustable on the rod to vary the normal spacing 18 between its inner end and the carriage. Each rod 15 projects at its outer end from its mounting part 16 in longitudinal register with the stem 59 of the respective valve 55 and in position for an outward movement of the rod from normal position to move the valve stem to open position.

In the operation of this feed control, it is set by an adjustment of the hand lever 4| for desired running conditions. In effecting such adjustment, the block 36 is moved to the right or left on the feed control rod 36, its movement to the right permitting a reduction in the fuel feed and its movement to the left effecting a tensioning of the spring 31 and causing a movement of the control rod to the left to increase the fuel feed until the tension of the spring 3'! is equalized with that of the opposing spring 34. It will be understood that during such adjustment of the fuel feed the trip sleeve 33 is retracted and held in such position by the trip pin 43 against the tension of the spring 35. During normal operation of the engine it functions on the two-stroke cycle principle, so that the cam 25 on the rack-bar 9 of the engine piston synchronizing means engages the roller on the pump plunger and actuates the pump to inject a fuel charge into the combustion chamber of the engine each time the pistons are substantially at the ends of their inner charge compressing movements. However, should either of the engine pistons fail to function properly, thereby throwing an'undue stress upon the rack-bars 8 and 9, or on the coacting pinion H, the pinion carriage it will move in the direction of the applied stress, If such movement is of sufiicient magnitude for the carriage to traverse the space 78 between it and the pin toward which it is moving and to move such pin to push valve rod 59 to open the coacting valve 55, the respective branch pressure line 49, 55 will be opened to the cylinder 46, thus instantly admitting pressure thereto to move the trip pin 43 outward to release the trip sleeve 33. Upon such release taking place, the sleeve 33 will be quickly moved to the right by the action of the spring 35 and will act through the spring 34 on the control rod 39 to move the pump-rack 22 the full extent to the right and shut off the pump fuel supply. The amount of effort required to cause the carriage 13 to shift from neutral position is determined by the adjusting screw 69 acting against the carriage springs H. The adjustment of the space 78 to determine the magnitude of movement of the carriage before one or the other of the pressure control valves 55 is opened is obtained by an adjustment of the stop collar ll on the control pin 15. An adjustment of the clearance spaces 18 may be compensated for by moving the entire valve unit '55 relative toits mounting screws El, thus maintaining proper relationship between the valve stem so and the rod :5.

' In the modification shown in Figs. 9 and 10, a relief valve 80 for the fuel injection pressure is provided in the fuel injection line 28 and is actuated upon predetermined movement of the pinion carriage block !3 in either direction, through an interposed lever 8!, to relieve the pressure in such line and cause a stopping of the engine.

The relief valve 8i), in the present instance. includes a casing 82 mounted on the tube and having a pressure relief passage 83 at each of two opposite sides of the tube and in communication therewith. Each of such passages is normally closed by a respective valve 84, the stem 85 of which projects outward from the tube through a guide opening in the casing 32 and is acted on by a spring 86 to normally hold the valve in closed position. The stems are radially opposed relative to the tube axis and an inward movement of either will move its valve inward to uncover the respective relief passage 83 to the tube passage, thus releasing the fuel injection presi sure in the tube,

The lever 8! is fulcrumed to one of the carriage block guide parts 66 and has one end forked and slidingly straddling a pin 81 on the carriage block l3 and its other end provided withtwo spaced arms 88 which span the valve 88, and each carries an adjustin screw 89 for engagement with the outer end of a respective valve stem 85 to open its valve upon a predetermined movement of the lever. When the carriage block I3 is in neutral position, each screw 89 is spaced a predetermined distance from its valve stem so that a relief valve is not opened until the carriage block has moved a predetermined distance in either direction from neutral.

In the modification shown in Figs. 11, 12 and 13, an electrically operated trip for the trip sleeve 33 of the fuel feed control is substituted for the hydraulically operated trip pin 43 of the means shown in Fig. 7. In the present form, the trip pin, designated 43* in Fig. 13, is held yieldingly engaged with the trip sleeve 33 by a spring il' and is released from the sleeve by the energizing of a solenoid 90 associated therewith. One end of the solenoid coil is grounded through a lead 9| while its other end is connected, through a control switch 92 and leads 93 and 94, to an electric current supply source 95; This switch, in the present instance, includes a frame 96 attached to the engine frame and having two spaced contacts 91, 91, Which are in connection with the positive side of the solenoid coil through the lead 93. These contacts are in normal predetermined spaced relation and each is permitted to move outward from such position against the tension of a spring 98. In the space between the two contacts 91 are mounted two floating contacts 99, 99, each carried by a respective oscillatory spring finger I90, and normally held thereby in spaced relation both to each other and to the contacts 97. The contacts 99 are connected by lead 94 to a battery or other suitable current supply source 55. A finger llll projects from the carriage block I 3 between the two contacts 99, and upon a predetermined movement of the carriage in either direction from neutral will move one or the other of said contacts,

depending on the direction of movement of thecarriage, into engagement with the companion contact 91, thus closing the solenoid circuit to effect a release of the trip pin.

If desired, the control for the rack bar 22 of the fuel pump I5 may have its off movement electrically actuated instead of utilizing electrical means to release the trip pin 63 to permit quick movement of the sleeve 33 to move the rack bar to oif position. This is illustrated in Fig. 14 wherein the pump rack bar 22 is yieldingly connected at one end to a manual control 33 and at its other end to a solenoid M5, the core H16 of which is attached to the rack bar while its coil l 01 is interposed in the line 93, 9| in place of the solenoid 98. It is apparent that when the solenoid I05 is energized the rack bar 22 is quickly moved to ofi position.

It is apparent that in the operation of the engine, full manual control is maintained over the quantity of oil injected by the fuel pump without interfering with the automatic action of the dephasin actuated stop means to shut off the fuel feed and stop the operation of the engine regardless of the governor or manualcontrol settings, and also that the automatic stopping means will be brought intoeifective action only by a predetermined magnitude of the dephasing stresses.

Inasmuch as the cushioning feature of the piston synchronizing means is itself novel and is usable alone to absorb and, reduce the shock loads of engines, especially when shocks are due to unequal loading, and also for use in connection with or to correct other operating features of the engine than the dephasing stop means herein described, it is separately claimed.

The floating feature of the pinion in the piston synchronizing mechanism is disclosed but not specifically claimed in a co-pending application Serial No. 558,360.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous.

modifications and changes without departing from the spirit of the claims.

Having thus described my invention, what. I claim as new, and desire to secure by United States Letters Patent, is:

1. In an internal combustion free piston en-,,

gine having a piston synchronizing means including a rack-bar projecting inwardly from and movable with each of the opposing free pistons, and pinion means-connecting and rotatable by opposing movements of the rack-bars, a carriage forming a mount for the pinion means and mounted for reciprocatory movements lengthwise of the rack-bar movements, and means normally holding said carriage in a predetermined neutral position and yieldable to relieve load shocks and piston dephasing strains on the pinion means.

2. In an internal combustion free piston engine having a piston synchronizing means including a pinion having connection with and reciprocally rotatable by inward and outward movements of the pistons, means carrying said pinion and movable lengthwise of the piston movements and operable to yieldingly hold the pinion with its axis in predetermined centered relation to the piston movements, whereby to compensate for load shocks and dephasin strains on the synchronizing means.

3. In an internal combustion free piston engine having a piston synchronizing means including a rack-bar projecting inward and movable with each of opposing free pistons, and a pinion connecting the rack-bars and tending to cause them to operate in synchronizing relation, a mountrotatably carrying said pinion and reciprocally movable lengthwise of the rack-bar movements, and means yieldingly holding the mount in a predetermined position of its movement whereby it may move from such position to relieve load shock or piston dephasing strains on the synchronizing means.

4. Inan internal combustion free piston engine having a piston synchronizing means including a, rack-bar projecting inward and movable with each of opposing free pistons, and a pinion connecting the rack-bars and tending to cause them to operate in synchronizing relation, a mount rotatably carrying said pinion and reciprocally movable lengthwise of the rack-bar movements, and a cushion acting on said mount at each end and tending to yieldingly hold it in a neutral position and to yield under load shock or piston dephasing strains on the synchronizing means.

5. In an internal combustion free piston engine having piston synchronizing means, movable means mounting a part of said synchronizing means, and means yieldingly holding said mount ing means in a neutral piston synchronized position and permitting movement thereoffrom such position to relieve load shock or pistondephasing strains on the synchronizing means.

6. In an internal combustion engine of the free piston type having a piston synchronizing means including reciprocally movable rack-bars, a connecting pinion means, and a shaft for the pinion means, means forming a guideway lengthwise of said rack-bar movements, a carriage guided for movements in said guideway and forming a mount for said shaft, nd cushion means for said carriage tending to hold it and the shaft in a neutral position and permitting yielding movements thereof to absorb load shocks and piston dephasing strains on the synchronizing means.

'7. In an internal combustion free piston engine having piston synchronizing means; movable means mounting a part of said synchronizing means, and means yieldingly holding said mounting means in a, neutral piston synchronized position and permitting movementthereof from such position to relieve load shock or. piston dephasing strains on the synchronizing means, together with i a fuel feed control means for the engine, meansfor actuating said control means to reduce the fuel feed, and means operable by predetermined movements of said mounting means from neutralposition to render said last named means active.

8. In an internal combustion free piston engine having piston synchronizing means, movable means mounting a part of said synchronizing means, and means yieldingly holding said mounting means in a neutral piston synchronized position-and permitting movement thereof from such position to relieve load shock or piston dephasing strains on the synchronizing means, together with a fuel feed means for the engine, and means operable to quickly move at least a part of said means to impart a predetermined fuel feed control movement thereto upon movement of said mounting means a predetermined extent from neutral.

9. In an internal combustion free piston engine having piston synchronizing means, movable means mounting a part. of said synchronizing means, and means yieldingly holding said mounting means in a neutral piston synchronized position and permitting movement thereof from such position to relieveload shock or piston dephasing strains on the synchronizing means, together with a fuel feed control means for the engine, trip means automatically operable when released to move at least a part of said control means to impart a predetermined fuel feed control movement thereto, and means operable by said mounting means when moved predetermined extent from neutral to effect a release of said trip means.

'10. In an internal combustion free piston engine having a periodically operable fuel charge means and a, piston synchronizing means, the latter including a rack-bar projecting inward from each piston and pinion means in meshing connection with said bars, a carriage for the pinion means mounted for yielding movements in either direction from neutral lengthwise of said rack-bars, control means for said fuel charge means operable to vary the fuel charge volume thereof, and means automatically operable by predetermined movement of said carriage from neutral upon occurrence of a dephased piston condition to render the pump inoperative.

11. In an internal combustion engine of the free piston type having fuel injection means, rackbarsprojecting inwardly from the pistons in lappin relation and a synchronizin pinion interposedbetween the bars in connection therewith, means carrying the pinion for movements lengthwise of the rack-bars when a dephased piston condition is present and for normally holding the pinion in a neutral position, and means operable by predetermined movements of the pinion carrying means from neutral position to render the fuel injection means inoperable to inject fuel charges into the engine.

12. In an internal combustion free piston engine having a piston synchronizing means including a rotatable pinion, and fuel charge feeding means, a control for said last means, means normally movable to actuate said control to reduce the fuel charges a predetermined extent; trip means operableto hold said last means against normal movement, a carriage carrying said pinion and mounted for reciprocatory movements transverse to the pinion axis and lengthwiseof the engine piston movements, means yieldingly resisting movement of the carriage from a neutral pinion position, and means rendered operative by a predetermined movement of the carriage from neutral position to release said trip means.

13. An arrangement as called for in claim 12 wherein the means which is operable to release the trip means is of a hydraulic nature.

14. An arrangement as called for in claim 12 wherein the means which is operable to release the trip includes a hydraulic pressure line, a normally closed valve in said line, and means movable by the carriage to open the line.

15. An arrangement as called for in claim 12 wherein the means which is operable to release the trip means is of an electrical nature.

16. In an internal combustion free piston engine having a fuel charge pump, and a piston synchronizing means, a control for said pump including a reciprocally movable member movable in one direction to increase the fuel charge and in the other direction to reduce the fuel charge, means movable to retracted position and operable when released from such position to quickly move said member a predetermined extent in charge reducing direction, and means rendered operable by said synchronizing means to release said retractable means from retracted position when a predetermined stress resulting from load shock or a dephased piston condition is applied to the synchronizing means.

17. In an internal combustion free piston engine having a fuel charge pump and a piston synchronizing means including a pinion, means mounting the pinion for yielding reciprocatory movements transverse to its axis and from neutral position when a stress resulting from load shock or a dephased piston condition is applied thereto, a fuel control for said pump operable to shut off the fuel charge supply, means normally held inactive and being operable, when released from inactive position, to effect a sudden movement ofsaid control to shut-01f position, trip means for holding said last means in inactive position, and means rendered operative by said pinion mounting means to release said trip means upon a predetermined movement of the pinion mounting means from neutral position.

18. In an internal combustion free piston engine, a piston synchronizing means, and a fuel charge pump having a reciprocally movable fuel charge control member, means yieldingly opposing movement of said member to increase the fuel charges, manually controlled means operable to yieldingly move said member in opposition to said yielding means, and to control movement of the member in the opposite direction to reduce the fuel charges, and means rendered operable by said synchronizing means when subjected to a predetermined strain caused by load shock or a dephased piston condition to quickly move said control member to predetermined charge reducing position against the tension of said yielding means and without disturbing an adjusted position of the manual control means.

19. In an internal combustion free piston engine, a fuel feed means, a piston synchronizing means with a part yieldlngly movable in response to piston dephasing stresses, means for actuating the fuel feed means to reduce the fuel feed, and means operable .by predetermined yielding movements of said part to render said last means active.

20. An arrangement as called for in claim 19 wherein the last-mentioned means includes an electrical control feature.

21. An arrangement as called for in claim 19 wherein the last-mentioned means includes a hydraulically operable control feature.

22. In an internal combustion free piston engine, a fuel feed means including a feed line, a valve in said line operable to render the fuel feed to the engine inoperative, a piston synchronizing means with a part yieldingly movable in response to piston dephasing stresses, and means connecting said part and valve to move it to inoperative fuel feeding position when a predetermined piston dephasing stress is applied to said part.

FRANK M. LEWIS. 

